1. Field of the Invention
This invention relates generally to a method of compressing flexible articles to a usable reduced size and more particularly to a method of compressing a plurality of flat stacked flexible articles into a compressed, compacted form which the articles will retain after removal of the applied pressure. The compacted articles can be subsequently returned to their original form and condition without the addition of additives or special procedures.
2. Description of the Prior Art
There are numerous available techniques for compressing fibrous articles but no known techniques for compressing a plurality of flat, stacked, non-woven, cotton and cotton blend flexible articles. For example, U.S. Pat. Nos. 2,659,935 (Hammon); 2,952,462 (Planin); 3,306,966 (Matejecek); 3,189,669 (Goldfein); 3,342,922 (Karpovich, et.al.); 3,504,064 (Bauer); and 4,529,569 (Palau) generally relate to methods for compressing a sponge material to a compacted, stable condition. A variety of techniques are disclosed in these patents, including the application of different agents, adhesives, temperatures, and pressures. In all cases, however, some type of liquid agent, usually water, is required to return the sponge article to its original, normal and expanded condition. Moreover, in all of these patents, the article has approximately the same configuration in the compressed and expanded conditions. Some of the patents, for example Bauer, require even more extreme conditions to return the article to its original shape; i.e. the application of both heat and steam.
There are also a number of patents relating to machines and methods for making tampons. See, for example, U.S. Pat. Nos. 2,134,930 (Reynolds); 2,336,744 (Manning): 2,425,004 (Rabell); and 2,462,178 (Ganz). These patents disclose a variety of different techniques for compressing fibrous materials to form tampons. These are notably different from the present invention. The material used is loose fibrous materials, as exemplified by the Manning patent, in which fibrous material enter through an opening and is deposited on the screen where air pressure causes it to form the pads. In addition, the nature of the product is such that there is no necessity for the product to be able to resume any original, uncompressed state in the absence of moisture. Further, many of these patents disclose quite elaborate folding or forming techniques. See, for example the Rabell patent.
U.S. Pat. No. 4,096,230 is another example of sponge material which is compressed and is capable of returning to an uncompressed condition. This reference again relies upon the use of moisture to return the sponge material to its original shape. The article is a dehydrated prothesis for insertion end-wise into a body opening; i.e. the ear canal, where it absorbs moisture and returns to its original shape.
In all known prior art cases, any compression of sheet articles to a compacted, solidified form, which is stable after the pressure has been released, requires the article to be soaked in water for it to return to its original loose and uncompressed state. In general, the technique used is somewhat unsophisticated with the applied pressure and other parameters not being significantly controlled. In many cases, operators are unaware of the exact conditions to which the articles are subjected. This technique is applied to such articles as face cloths where it is acceptable to soak them in water to return the articles to their original state. Since a face cloth is wet prior to use, soaking it to bring it back to its original size is not detrimental or disadvantageous.
U.S. Pat. No. 4,421,007 (Tanaka et.al.) is an example of the technique for producing a compressed cloth-like article which can be returned to its original state by absorption of water. Thus, this patent is intended for use on face cloths and the like and suggests the use of very high pressures, in the range of 1,100 to 1,500 kilograms per square centimeter, and preferably 1,200 to 1,300 kilograms per square centimeter. This significant pressure range is equivalent to pressures of 15,640 psi to 21,330 psi. In light of the discoveries made by the present applicant, these pressures are extraordinarily high.
Applicant has discovered that, for a variety of materials, pressures in excess of a few thousand psi result in unacceptable creases thereby making the article unmarketable. The Tanaka et. al. patent refers to a process which utilizes a pressure as low as 30 kilograms per square centimeter or approximately 425 psi. Again, this apparently is for an article which can be recovered to its original state only by absorbing water. The Tanaka et. al. patent discusses in its examples the use of a binderless cellulosic non-woven fabric. Binderless cellulosic non-woven fabric appears to be higher in compression elasticity, thereby requiring higher pressures to ensure a well compressed product which is not wrinkled at the edges. Indeed, the example uses a control at a pressure of 1,000 kilograms per square centimeter to show that the compression and molding is inadequate at this pressure.
In many cases, wetting a compressed article as purchased in order to return it to an original uncompressed condition for use is entirely unacceptable. In effect, a user would have to first wet the article to loosen and expand it, and subsequently dry the article.
It has been discovered, while working with non-woven, particularly knitted articles, that a plurality of flat sheets of such articles can be dramatically reduced in volume. Compacting such articles can bring about significant environmental benefits in that it will reduce the exterior packaging by a minimum of 10% to a maximum of 60%. It will also reduce transportation costs which directly contribute to environmental hazards.
The wide range of articles which can utilize the present form of compacting, and packaging can also save costs associated with handling and warehousing.